text: /****************************************************************************
   * fs/vfs/fs_fstatfs.c
   *
   *   Copyright (C) 2017 Gregory Nutt. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   * 3. Neither the name NuttX nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
   * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <sys/statfs.h>
  #include <string.h>
  #include <limits.h>
  #include <sched.h>
  #include <errno.h>
  
  #include "inode/inode.h"
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: fstatfs
   *
   * Return: Zero on success; -1 on failure with errno set:
   *
   *   EACCES  Search permission is denied for one of the directories in the
   *           path prefix of path.
   *   EFAULT  Bad address.
   *   ENOENT  A component of the path path does not exist, or the path is an
   *           empty string.
   *   ENOMEM  Out of memory
   *   ENOTDIR A component of the path is not a directory.
   *   ENOSYS  The file system does not support this call.
   *
   ****************************************************************************/
  
  int fstatfs(int fd, FAR struct statfs *buf)
  {
    FAR struct file *filep;
    FAR struct inode *inode;
    int ret;
  
    DEBUGASSERT(buf != NULL);
  
    /* Did we get a valid file descriptor? */
  
    if ((unsigned int)fd >= CONFIG_NFILE_DESCRIPTORS)
      {
        /* No networking... it is a bad descriptor in any event */
  
        set_errno(EBADF);
        return ERROR;
      }
  
    /* The descriptor is in a valid range to file descriptor... do the
     * read.  First, get the file structure.  Note that on failure,
     * fs_getfilep() will set the errno variable.
     */
  
    filep = fs_getfilep(fd);
    if (filep == NULL)
      {
        /* The errno value has already been set */
  
        return ERROR;
      }
  
    /* Get the inode from the file structure */
  
    inode = filep->f_inode;
    DEBUGASSERT(inode != NULL);
  
    /* The way we handle the stat depends on the type of inode that we
     * are dealing with.
     */
  
  #ifndef CONFIG_DISABLE_MOUNTPOINT
    if (INODE_IS_MOUNTPT(inode))
      {
        /* The node is a file system mointpoint. Verify that the mountpoint
         * supports the statfs() method
         */
  
        ret = -ENOSYS;
        if (inode->u.i_mops && inode->u.i_mops->statfs)
          {
            /* Perform the statfs() operation */
  
            ret = inode->u.i_mops->statfs(inode, buf);
          }
      }
    else
  #endif
      {
        /* The node is part of the root pseudo file system */
  
        memset(buf, 0, sizeof(struct statfs));
        buf->f_type    = PROC_SUPER_MAGIC;
        buf->f_namelen = NAME_MAX;
        ret            = OK;
      }
  
    /* Check if the fstat operation was successful */
  
    if (ret < 0)
      {
        set_errno(-ret);
        return ERROR;
      }
  
    /* Successfully statfs'ed the file */
  
    return OK;
  }
  